Such belt conveyor devices having a displaceable transfer point between two upper belt sections for changing the lengths are known per se. As is the case with the device shown in DE 43 41 044, for example, these are used in food processing operations for “formatting”, in order to line up products that are lying on the belt with nonuniform spacing into a uniform sequence on the discharge section of the conveyor belt, or to isolate individual packages from products lined up uniformly on the entry section. Reference is also made to DE 691 92 859 and DE 1 456 521, which show such belt conveyors, each of which comprises conveyor belts having a displaceable transfer point and each comprising a chain supporting one of the conveyor belts, having evenly spaced rollers. By way of the displaceable transfer point, a certain buffer effect for the transported objects, for example, packaged food, can also be achieved here.
Document DE 10 2009 019 462 also shows such a device, with which a certain number can be picked from a row of products initially disposed at a distance from each other, and can be “pushed together” to form multipacks of a defined size. This device also makes it possible to achieve a certain “buffer” in the flow of products by temporarily holding the products back.
However, the known devices have the problem that the flexibility thereof is limited in terms of the variable length of the upper belt sections. In particular, the upper belt sections cannot be lengthened beyond a certain extent without these sagging to an unacceptable extent due to the weight of the products lying thereon. Such sagging impairs the buffering function and, primarily, the function of defined formatting.
A further problem is that the known conveyor devices have only limited suitability for transporting unpackaged foodstuffs that lie directly on the surface of the conveyor belts. Finally, all the known conveyor devices comprise a deflection roller at some point, which acts on the conveyor belt on this surface. Since the belt can become contaminated via the contact of this deflection roller, greater effort is required to maintain cleanliness and hygienic conditions.
The problem addressed by the present invention is therefore that of providing a device that can be implemented using technically simple means and that reduces the sag of the conveyor belts to a minimum and, therefore, provides increased flexibility in terms of the variable length at a high conveyance speed.
This problem is solved by the present invention.